Check your fuel containers for any water, even a few drops is enough to cause issues.
Be mindful of where you store your fuel jugs. Don't need rain to get in them.
Whenever you're using the power washer, be careful about spraying it with water.
Don't leave your fuel jug sitting where the water can reach it while you're spraying.
Ethanol blended fuels absorb moisture from the air. Yeah, even the overspray from pressure washing sneaks in, a little bit at a time.
I personally run non-Ethanol fuel.
This site is a pretty good starting place to help locate it, if you want to run non-Ethanol fuel.
Pure-gas.org is the definitive web site listing stations that sell pure gasoline in the U.S. and Canada.
www.pure-gas.org
And there are folks here who will mention that Ethanol hasn't given them any problems.
All I can say on that, Is I'm seriously flipping jealous

of the fuel blend their area is getting.
Trying to pinch a water hose and change connections or some such, can get a blast of water in places that we wouldn't think matters or realize happened "
just that quick?"
I keep a cut-off valve and quick connect couplings on the outlet end on my garden hoses.
Buy the good brand ones made from brass, not the plastic ones..
Little pricey to go with all brass fittings, no doubt.
But once you live with the quick connects for a summer or so, I honestly think You'll wonder why it took you so long to set up your hoses, sprinklers, nozzles, etc.
And You'll need to buy a male fitting for every doggoned thing that needs water hooked up.
It'll be a little pinch in the pocket to get all of the bits at first.
And yes, that leaky hose connection also needs a good washer, O-ring, gasket, installed so that it isn't spraying water on~in the engine or fuel jug.